Adrian Peterson was indicted by a grand jury on one count of ‘reckless of negligent injury to a child’.
Photograph: Ann Heisenfelt/AP

Reggie Bush, the Detroit Lions running back, called in to a radio station in defence of Adrian Peterson, indicted by a grand jury on charges of “reckless or negligent injury to a child.” Bush told listeners of WFAN: “I have a one-year-old daughter, and I discipline her. I definitely will try to … will obviously not leave bruises or anything like that on her. But I definitely will discipline her harshly depending on what the situation is.”

It is an admission that to some, would seem shocking: that a father would admit to beating a one-year-old, and confess without shame that the discipline would be harsh. “I was punished the same way,” he added.

But the Peterson case has revealed that such attitudes, at least in some places in the United States, are far from uncommon. And it has exposed the immense gulf that exists between standards in child discipline in the US. An action that for some amounts to child abuse is regarded to others as routine – even essential – parenting.

Take how Peterson describes how he beat his four-year-old son, in the police report obtained by CBS in Houston. The report tells in great detail how Peterson stripped a branch of its leaves, and whipped the boy on the bare buttocks and legs until it raised welts – all information volunteered by Peterson and his son. The four-year-old was also hit in the testicles, the report said, and had defensive injuries on his hands where he had tried to protect himself.

Peterson allegedly told the child’s mother by text that he felt bad about how much he had hurt his son, especially as he had: “Got him in nuts once.” The report continued:

Peterson estimated he “swatted” his son “10 to 15” times, but he’s not sure because he doesn’t “ever count how many pops I give my kids.” Peterson went on to reiterate again how much he loves all his kids, and only “whoops” them because he wants them to do right.

Toward the end of the interview, Peterson said he would reconsider using switches in the future, but said he would never “eliminate whooping my kids … because I know how being spanked has helped me in my life.”

The report is striking for the extraordinary national cognitive dissonance it highlights. Peterson – giving the police interview before the story broke nationally, and public opprobrium poured in – simply doesn’t realise he has done something that anyone could consider even bad parenting, let alone child abuse.

Later, after public condemnation had descended upon him – and after he realised that not only had he offended the public, but may have committed a crime, Peterson made a statement as plaintive as it is bewildered: “I never imagined being in a position where the world is judging my parenting skills, or calling me a child abuser,” he said.

“I have to live with the fact that when I disciplined my son the way I was disciplined as a child, I caused an injury that I never intended or thought would happen.”

Vikings general manager Rick Spielman said: ‘This is a difficult path to navigate regarding the judgment of how a parent disciplines a child.’ Photograph: Jerry Holt/AP

The Vikings at first suspended Peterson for just one game, then reversed that decision Wednesday night to ban him. “This is a difficult path to navigate regarding the judgment of how a parent disciplines his child,” Rick Spielman, the general manager of the Vikings at first. “We believe he deserves to play while the legal process plays out.”

The problem is that both in law and in culture, the line between discipline and child abuse is blurred. To some extent Barkley’s point about the south is well-taken – the national opinion, especially among academic psychologists, has moved on faster than local culture and behaviour, to the point where what is considered normal in some regions and families is clearly abusive when seen by the national eye.

“It’s definitely true that corporal punishment is more common in African American, and lower income families – not that those are the same groups – and more in the south,” said Elizabeth Gershoff, an associate professor of social ecology at the University of Texas, Austin.

There are state laws against corporal punishment in schools in all but 19 states, but almost all of the states in which it remains legal are in the south – including Texas.

But corporal punishment in the home is legal in all 50 states, with murky caveats. According to the office of the attorney general of Texas: “Any form of corporal punishment may be abusive if it results in injury.” This is a common line. In all states, the definition of where the line is drawn is “reasonable” force, with prosecutors or juries left to decide on what constitutes reasonable. Peterson was indicted specifically because he left marks on his son’s body.

On top of that, in 1977 the supreme court ruled that the eighth amendment protection against “cruel and unusual punishment” did not apply to schoolchildren, after hearing a case in which students were hit regularly with paddles for minor infractions, one “depriving him of the use of his arms for a week,” and one student was hit so severely “that he suffered a hematoma requiring medical attention.”

The ruling has not been re-tested since, and there are still no federal statutes governing corporal punishment in children. The US is one of only three non-signatories to the UN Convention on the Rights of the Child – the other two are South Sudan and Somalia.

“As a country, we’ve managed to draw the line [between discipline and abuse] in a rather vague place,” said Andrew Grogan-Kaylor, an associate professor of social work at the University of Michigan who specialises in parenting behaviors and punishment. “The way our system is set up, state-level legislation is going to come into play, and its going to be up to child local welfare authorities and local police.”

“What Peterson did probably wouldn’t even be prosecutable in most part of the country quarter of a century ago,” said Victor Vieth, executive director emeritus of the Gundersen National Child Protection Training Center. “Today, in most parts of the country it would be. The whole country is changing.”

“I would venture a guess that hitting a kid with a stick would be considered chargeable in almost any state,” said Joan Meier, a professor of clinical law at George Washington University. “The irony [of Peterson saying] that this is how he was raised, well … many people who are wife-beaters were raised in abusive families. We still made that a crime, because we have moved on.”

We may not have moved on all that far. A Harris Interactive poll in 2013 found that 81% of Americans say that parents spanking their children is at least sometimes appropriate, and 67% said they had spanked their child. Eighty-six percent of respondents said they were spanked as a child, and 21% said that there were times when they had been spanked with “too much violence.”

Even among people who self-defined as having a liberal political philosophy, just 29% thought spanking was never appropriate. In fact, the only group that was starkly different in its views on spanking was the minority who reported not having been spanked themselves as children; in this group, 50% said that spanking a child was never appropriate.

“It’s interesting to me how the vagueness of our statutory environment stands in contrast to the research,” Grogan-Kaylor said, “which is unanimous in the view that this is a continuum of violence. In the US we set aside smacking or spanking and refer to it as ‘customary discipline,’ but the research suggests that even a little is too much.”

Ruben Anguiano, an associate professor of human development and educational psychology at the University of Colorado, Denver, said that the consensus of developmental psychology in the US had already moved away from corporal punishment, and that the country was following – but slowly. “We realise there’s better ways of doing it,” he said.

“Religion plays a part,” he continued. “The whole ‘spare the rod, spoil the child’ [mentality] is very monolithic.”

“Theres a lot of things that my parents generation did that were not great that I wouldn’t repeat with my kids,” said Gershoff. “My parents didn’t have seatbelts. Just because I turned out OK, doesn’t mean I’m going to do that to my kids. We know better know.”